This invention primarily addresses the general problem of application of high-speed cutters to the specialty apparel industry. The essence of the current invention is a method and apparatus designed to rapidly sort garment pieces cut from a single layer of cloth into an order suitable for assembly. The techniques invented, however, can also be applied to non-garment pieces.
The most likely development in high-speed cutters in the apparel industry is large-scale use of laser cutters. The speed of conventional cutters, which include hand cutters and automated blade cutters, ranges from roughly 8-20 inches per second. Economically practical laser cutters make cutting speeds of several hundred inches per second possible, thus offering the potential for a 10 to 20-fold increase in cutting speed relative to current commercial apparatus.
Such an increase in cutting speed, however, must be accompanied by consistent increases in the rate of handling of cut pieces, or the faster cutting speed will be of little benefit. The fastest commercial technique at present involves automated mechanical cutters which operate on a large conveyor which positions a fixed length of fabric under the active area of the cutter. The fabric usually is fed into the system from a large rolled bolt of material. The pieces to be cut from the fabric are laid out in a pattern called a marker, which contains the cutting instructions to produce a number of complete garments of various sizes. A single garment is never divided between two markers.
Garments are always laid out on markers, and the length of a marker is the length over which the cutting pattern is repeated. In current practice a marker generally ranges from 10 to 35 yards long, containing all the pieces for 6 to 15 garments (these are not fundamental limits). The fabric is passed under the active area of the cutter, which then performs the preprogrammed cuts. The information for the cuts is stored in a file much like that used to guide a computer controlled machine tool. The cut garment pieces are then transported (usually by conveyor) to a sorting and collating area, where the garment pieces are separated into piles, each pile containing the parts required to assemble a single garment. These piles are then taken to assembly stations.
The process of assembly is greatly simplified if the garment parts appear in the pile in the order in which they will be assembled. As assembly of the relatively small numbers of garments made using this type of process is usually carried out by manual sewing, proper collation of the pieces before the pile arrives at the manual assembly station greatly improves the throughput of the overall system. This is no simple task, however, as for example the first piece defined by the marker pattern may be the tenth piece to be assembled. In addition, the order of pieces within the marker pattern for different garments will vary, as will the sizes and even the identities of the garments to be assembled. Accordingly, collation of the cut garment pieces is of crucial importance for maximizing the throughput of the garment assembly line.
It would seem that proper design of the marker pattern could greatly simplify the problem of sorting. Unfortunately, the layout of the marker pattern is a highly constrained problem, and ease of piece collation is only one of the constraints. Other constraints include the fact that a fixed number of garments often possessing a range of sizes must fit in the marker, pieces on the marker must be placed so that dye and color variations across the width and length of the fabric are not noticeable in the finished garment, and fabric waste must be minimized. Waste of fabric is especially disagreeable, as this is an industry with massive competition and a small profit margin. Accordingly, the marker patterns are often very convoluted. When combined with the second major constraint listed above, it is not surprising that handling and collation of garment pieces represents a major bottleneck in throughput of garment production. The speed of current cutting technologies is slow enough that these difficult process steps are handled manually with little loss in overall production. However, a massive increase in cutting speed, as is offered by laser cutting, requires a new approach to handling and collation of cut garment pieces.
For the foregoing reasons, there is a need for a new approach to handling and collation of garment pieces cut from a marker pattern which allows operation compatible with cutting speeds vastly greater than those currently used. A further need is for equipment capable of carrying out the abovementioned new approach, yet remaining compatible with a wide variety of garment designs.